1. Technical Field of the Invention
The present invention relates to a picking apparatus for a fluid jet loom and, more particularly, to a technique for automatically setting, in setting up a fluid jet loom for weaving a new fabric, a pick length accurately corresponding to a target pick length by increasing or decreasing a tentative pick length in a weft yarn measuring and storing device comprising a mechanism capable of changing set pick length, and capable of winding and storing a predetermined length of weft yarn on a measuring drum by means of a rotary yarn guide after the weft yarn has been checked.
2. Background Art
In a fluid jet loom, new weaving conditions weaving a new fabric is set before starting the loom for the normal weaving operation. A set pick length is one of those weaving conditions. The set pick length must be appropriate and accurate because an excessive set pick length increases waste yarn.
In such a drum type weft yarn measuring and storing device, a necessary pick length is set by changing the number (an integral number) of turns of a weft yarn on a measuring drum, by changing the diameter of the measuring drum or by changing a regular sequential selection of the releasing positions and the checking positions on the measuring drum. When a set pick length adjusting range is smaller than the length of one turn of the weft yarn on the measuring drum, a necessary pick length is set by changing the diameter of the measuring drum or by changing the regular sequential selection of the releasing positions and the checking positions. Such pick length setting methods are disclosed in U.S. Pat. No. 4,595,039 and Japanese Laid-Open Patent Publication Nos. 57-29640, 60-28550 and 60-28552. In either one of those pick length setting methods, setting an optimum pick length is impossible even if a target pick length is decided on the basis of the calculated circumference of the measuring drum or the regular sequential selection of the releasing positions and the checking positions is determined through calculation, because the tension of the weft yarn in measuring and winding the same on the measuring drum, the physical properties of the weft yarn, the type of the weft yarn and the process of manufacturing the weft yarn exert subtle influence on the actual pick length.